Introduction to Event Hub with Node.js (Beginner Friendly Guide)

Azure Event Hub is a big data streaming platform and event ingestion service—capable of receiving and processing millions of events per second. Think of it as a high-speed highway for streaming data, ideal for telemetry, logs, and real-time analytics.

In this article, you’ll learn:

• What is Event Hub and how it works

• How to set it up in the Azure Portal

• How to send and receive messages using Node.js

• How to store the event stream into Blob Storage using Capture

Let’s break it down step-by-step.

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🧠 What is Azure Event Hub?

Azure Event Hub works like a message pipeline where:

• Producers send messages (called events)

• Event Hub receives and stores them temporarily

• Consumers process those messages in real-time

It is ideal for:

• IoT telemetry data

• Application logs

• Clickstream or app usage analytics

• Real-time monitoring pipelines

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🛠️ Step-by-Step Setup in Azure Portal

1. Create an Event Hub Namespace

This is like a container for your Event Hubs.

• Go to Azure Portal → Search for Event Hubs

• Click + Create

• Choose your subscription, resource group, and region

• Create a Namespace (e.g. event-hub-testing-01)

• Choose Pricing Tier (start with Basic)

2. Create an Event Hub (under that namespace)

• After the namespace is deployed, click + Event Hub

• Name it something like eventhub01

• Leave default partition count (2)

• Click Create

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3. Get the Connection String

You’ll need this to send events.

• Go to the Shared Access Policies tab

• Click on RootManageSharedAccessKey

• Copy the Connection string–primary key

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💻 Sending Events with Node.js

Install the package:

npm install @azure/event-hubs

send.js

const { EventHubProducerClient } = require("@azure/event-hubs");

const connectionString = "<YOUR_CONNECTION_STRING>";
const eventHubName = "eventhub01";

async function main() {
  const producer = new EventHubProducerClient(connectionString, eventHubName);

  const eventDataBatch = await producer.createBatch();
  eventDataBatch.tryAdd({ body: "Hello from Node.js!" });

  await producer.sendBatch(eventDataBatch);
  console.log("✅ Event sent!");

  await producer.close();
}

main().catch((err) => {
  console.error("❌ Error sending event:", err);
});

Run it:

node send.js

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📥 Receiving Events with Node.js

receive.js

const { EventHubConsumerClient } = require("@azure/event-hubs");

const connectionString = "<YOUR_CONNECTION_STRING>";
const eventHubName = "eventhub01";
const consumerGroup = "$Default"; // or your custom one

async function main() {
  const client = new EventHubConsumerClient(consumerGroup, connectionString, eventHubName);

  const subscription = client.subscribe({
    processEvents: async (events, context) => {
      for (const event of events) {
        console.log("📩 Received:", event.body);
      }
    },
    processError: async (err, context) => {
      console.error("❌ Error:", err);
    }
  });

  // Stop after 30s
  setTimeout(async () => {
    await subscription.close();
    await client.close();
    console.log("⏹ Stopping subscription...");
  }, 30000);
}

main().catch(console.error);

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📦 Enable Capture to Store Events in Blob Storage

This helps in storing a backup or analyzing events later.

Steps:

1. Go to your Event Hub Instance

2. Click on Capture in the left menu

3. Choose:

   • Capture Provider: Azure Storage Account

   • Select a valid Storage Account + Container (create one if needed)

   • Use default file format templates

⚠️ If you're getting an error like “Unknown capture destination type”, it means you haven't created a proper Storage Account yet.

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🔄 Verify Event Flow

You can check:

• Incoming events under the Metrics tab

• Stored .avro files in the Blob Storage container

To convert .avro to JSON, you can use avro-tools or online tools.

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✅ Summary

You’ve now:

• Created and configured Event Hub

• Sent and received events using Node.js

• Captured events to Azure Blob Storage

This gives you a solid foundation for building real-time analytics pipelines, telemetry systems, or log processors.